<HTML> <!-- Copyright (c) Jeremy Siek 2000 Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) --> <Head> <Title>Boost Graph Library: Depth-First Visit</Title> <BODY BGCOLOR="#ffffff" LINK="#0000ee" TEXT="#000000" VLINK="#551a8b" ALINK="#ff0000"> <IMG SRC="../../../boost.png" ALT="C++ Boost" width="277" height="86"> <BR Clear> <H2><A NAME="sec:dfs"></A> <img src="figs/python.gif" alt="(Python)"/> <TT>depth_first_visit</TT> </H2> <P> <PRE> template <class <a href="./IncidenceGraph.html">IncidenceGraph</a>, class <a href="./DFSVisitor.html">DFSVisitor</a>, class ColorMap> void depth_first_visit(IncidenceGraph& g, typename graph_traits<IncidenceGraph>::vertex_descriptor s, DFSVisitor& vis, ColorMap color) template <class <a href="./IncidenceGraph.html">IncidenceGraph</a>, class <a href="./DFSVisitor.html">DFSVisitor</a>, class ColorMap, class TerminatorFunc> void depth_first_visit(IncidenceGraph& g, typename graph_traits<IncidenceGraph>::vertex_descriptor s, DFSVisitor& vis, ColorMap color, TerminatorFunc func = TerminatorFunc()) </PRE> <P> This function visits all of the vertices in the same connected component as the source vertex <tt>s</tt>, using the <a href="./graph_theory_review.html#sec:dfs-algorithm">depth-first pattern</a>. The main purpose of the function is for the implementation of <TT>depth_first_search()</TT> though sometimes it is useful on its own. <p> The <tt>DFSVisitor</tt> supplied by the user determines what actions are taken at each event-point within the algorithm. <p> The <tt>ColorMap</tt> is used by the algorithm to keep track of which vertices have been visited. <p>The second variant can be used, for example, to find all marked vertices reachable from a start vertex by a path which does not contain any another marked vertices. <P> <h3>Where Defined:</h3> <a href="../../../boost/graph/depth_first_search.hpp"><TT>boost/graph/depth_first_search.hpp</TT></a> <h3>Parameters</h3> IN <tt>IncidenceGraph& g</tt> <blockquote> A directed or undirected graph. The graph's type must be a model of <a href="./IncidenceGraph.html">Incidence Graph</a>.<br> <b>Python</b>: The parameter is named <tt>graph</tt>. </blockquote> IN: <tt>vertex_descriptor s</tt> <blockquote> The source vertex from which to start the search.<br> <b>Python</b>: The parameter is named <tt>root_vertex</tt>. </blockquote> IN: <tt>DFSVisitor visitor</tt> <blockquote> A visitor object that is invoked inside the algorithm at the event-points specified by the <a href="./DFSVisitor.html">DFS Visitor</a> concept. The visitor object is passed by value <a href="#1">[1]</a>.<br> <b>Python</b>: The parameter should be an object that derives from the <a href="DFSVisitor.html#python"><tt>DFSVisitor</tt></a> type of the graph. </blockquote> UTIL: <tt>ColorMap color</tt> <blockquote> This is used by the algorithm to keep track of its progress through the graph. The type <tt>ColorMap</tt> must be a model of <a href="../../property_map/doc/ReadWritePropertyMap.html">Read/Write Property Map</a> and its key type must be the graph's vertex descriptor type and the value type of the color map map must model <a href="./ColorValue.html">Color Value</a>.<br> <b>Python</b>: The color map must be a <tt>vertex_color_map</tt> for the graph. </blockquote> IN: <tt>TerminatorFunc func</tt> <blockquote> A function object callable with two parameters - the descriptor of vertex and the graph instance - and returning bool. The call is made immediately after call to 'discover_vertex' visitor event. If <tt>true</tt> is returned, the out edges of the vertex are not examined, as if they don't exist.<br> <b>Python</b>: Unsupported parameter. </blockquote> <P> <h3>Complexity</h3> Time complexity is <i>O(E)</i>. <h3>Notes</h3> <p><a name="1">[1]</a> Since the visitor parameter is passed by value, if your visitor contains state then any changes to the state during the algorithm will be made to a copy of the visitor object, not the visitor object passed in. Therefore you may want the visitor to hold this state by pointer or reference. <br> <HR> <TABLE> <TR valign=top> <TD nowrap>Copyright © 2000-2001</TD><TD> <A HREF="http://www.boost.org/people/jeremy_siek.htm">Jeremy Siek</A>, Indiana University (<A HREF="mailto:jsiek@osl.iu.edu">jsiek@osl.iu.edu</A>) </TD></TR></TABLE> </BODY> </HTML>